﻿#region Copyright and License Notice
// Copyright (C)2010-2016 - Rob Levine and other contributors
// http://configgen.codeplex.com
// 
// This file is part of ConfigGen.
// 
// ConfigGen is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
// 
// ConfigGen is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
// 
// You should have received a copy of the GNU General Public License and 
// the GNU Lesser General Public License along with ConfigGen.  
// If not, see <http://www.gnu.org/licenses/>
#endregion

using System.IO;
using System.Xml;
using System.Xml.Serialization;
using ConfigGen.Core.TemplateProcessing;

namespace ConfigGen.Core.TemplateLoader
{
    /// <summary>
    /// Loads and returns any template preferences from the template xml file.
    /// </summary>
    public class TemplatePreferencesLoader : ITemplatePreferencesLoader
    {
        /// <summary>
        /// Returns the template preferences specified in the xml template, or the defaults if none specified, and removes the template preferences node from the template.
        /// </summary>
        /// <param name="sourceTemplateStream">Stream containing the source template stream.</param>
        /// <param name="destinationTemplateStream">Stream into which to write the template after the preferences section has been extracted.</param>
        /// <returns>Template preferences specified in the xml template, or the defaults if none specified.</returns>
        public TemplatePreferences LoadPreferences(Stream sourceTemplateStream, Stream destinationTemplateStream)
        {
            var xmlDocument = new XmlDocument();
            var xmlNamespaceManager = new XmlNamespaceManager(xmlDocument.NameTable);
            xmlNamespaceManager.AddNamespace("cg", TemplateProcessor.ConfigGenXmlNamespace);
            xmlDocument.Load(sourceTemplateStream);
            var preferencesSectionList = xmlDocument.SelectNodes("/node()/cg:TemplatePreferences" ,xmlNamespaceManager);

            var preferences = new TemplatePreferences();

            if (preferencesSectionList != null
                && preferencesSectionList.Count > 0)
            {
                if (preferencesSectionList.Count > 1)
                {
                    throw new TemplateLoadException(
                        "An expcetion occurred loading the template as more than one TemplatePreferences section was found");
                }
                var preferencesSection = preferencesSectionList[0];
                var serializer = new XmlSerializer(typeof (TemplatePreferences));
                using (var memoryStream = new MemoryStream())
                using (var writer = XmlWriter.Create(memoryStream))
                {
                    preferencesSection.WriteTo(writer);
                    writer.Flush();
                    memoryStream.Position = 0;
                    preferences = (TemplatePreferences) serializer.Deserialize(memoryStream);

                    xmlDocument.DocumentElement.RemoveChild(preferencesSection);
                }
            }

            xmlDocument.Save(destinationTemplateStream);
            return preferences;
        }
    }
}
